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Zilmax was used in cattle to put on more muscle and less fat late in the feeding period.

The five-step plan included commitments to re-certify users and handlers of the product, initiate a scientific audit, reinforce appropriate management practices, and form an advisory board to review data.

"The findings that come as a result of the plan will add to the significant amount of data that already exists for Zilmax including numerous animal safety and well-being trials," a Friday statement from Merck said.

However, a timeline for returning Zilmax to the market has not been established.

"At Merck Animal Health, we continually evaluate our processes and procedures across the entire company to ensure that we maintain the best science-based practices and procedures for the health and well-being of animals," says KJ Varma, BVSc, Ph.D., Merck's Senior Vice President Global R&D. "Our five-step plan is a direct reflection of that commitment to science."

Certification Process

As part of the five-step process, Merck said that a formal certification process has been developed. As part of the certification, every feedyard team member, nutritionist and veterinarian who uses Zilmax or provides consultative services on feeding Zilmax to cattle must be trained annually on the proper use of the product.

The training will focus on safety practices, product handling, mixing protocols, cattle management, product inventory, record keeping and clean-out procedures. Every certified operation will also be required to pass an initial homogeneity test to ensure proper mixing practices, as well as four additional feed mix tests throughout the year, Merck says.

Before a feedyard can participate in the Zilmax Field Evaluations, the operation will need to be certified.

Zilmax Field Evaluations

In addition to implementing the certification process, the company has also worked to finalize field evaluations for Zilmax-fed and control cattle (previously noted as "scientific audit"), which are expected to begin at the beginning of 2014.

The field evaluations will take place with the oversight of an independent veterinarian, Merck says, who will serve as principal investigator and collect all data, analyze results and publicly communicate findings in support of the company's commitment to transparency and communication.

"We at Merck Animal Health remain highly confident in the safety of Zilmax," Varma's statement concluded. "We believe the field evaluations we are conducting as part of the five-step plan will support the results of previous studies and the safety of the product, and we are confident that they will help create a greater understanding of the best management practices that are so vital to helping ensure the well-being of cattle."